Control for gas appliances

ABSTRACT

A valve head in a gas valve through which gas is supplied to a gas-fired appliance is actuated by a diaphragm exposed on one side to liquid pressure generated by a centrifugal pump driven by an electric motor.

United States Patent Inventor Appl. No.

Filed Patented Assignee Alan Launchbury Birmingham, England 743,208

July 8, 1968 Jan. 19, 1971 Sperryn 8: Company Limited Birmingham,England a British Company CONTROL FOR GAS APPLIANCES 1 Claim, 2 DrawingFigs.

US. Cl l37/492.5 Int. Cl F16k 31/145 Field ofSeal'ch l37/487.5,

[56] References Cited UNITED STATES PATENTS 1,302,538 5/1919 Gulick137/413 2,203,243 6/1940 Wettstein. 137/492.5X 3,051,432 8/1962 Sullivan25 1/5 7X Primary Examiner-M. Cary Nelson Assistant Examiner-R. B.Rothman Att0rneyScrivener, Parker, Scrivener and Clarke ABSTRACT: Avalve head in a gas valve through which gas is supplied to a gas-firedappliance is actuated by a diaphragm exposed on one side to liquidpressure generated by a centrifugal pump driven by an electric motor.

PATENTEU JAN] 9197:

oN WW MN mm N mE CONTROL FOR GAS APPLIANCES This invention relates tonew or improved control means for controlling the supply of gas togas-fired appliances.

According to our invention a valve through which gas is supplied to agas-flred appliance is actuated by a diaphragm exposed on one side toliquid pressure generated by a centrifugal pump driven by an electricmotor.

The valve head is conveniently urged by a spring into engagement with aseat between a gas inlet and an outlet leading to the appliance and isadapted to be moved away from the seat by the diaphragm exposed to theliquid pressure, and that pressure is controlled by means sensitive tothe outlet pressure of the gas whereby the pressure of the gas suppliedto the appliance is maintained substantially constant.

The pressure of the liquid may also be controlled by thermostatic meanssensitive to the temperature in the appliance to maintain thattemperature within predetermined limits.

The arrangement provides a very smooth and accurate control of the rateof opening of the valve and of the rate at which gas is supplied to theappliance.

Our improved valve is particularly suitable for use with natural gas andother gases containing a high proportion of methane. i I

A practical form of valve limit in accordance with our invention isillustrated in the accompanying drawings in which:

FIG. 1 is a vertical section of the unit; and

FIG. 2 is atransverse section on the line 2-2 of FIG. 1. k

In the unit illustrated the valve and the pump by which it is actuatedand controlled are mounted in a common housing Gas enters the unitthrough an inlet 11 at one end and leaves by an outlet 12 at theopposite end.

The flow of gas is controlled by valve head 13 cooperating with a seat14 which may be integral with the housing, but preferably it is aseparate insert sealed by an ring 15. The valve head which is urgedupwardly. into engagement with the seat by a light spring 16 is mountedon a stem 17 which extends upwardly through a passage 18 leading fromthe inlet to the valve seat, and above that passage the stem is carriedthrough and secured in a cup 19 working in and connected by a rollingdiaphragm 21 to a cap 22 mounted in the housing.

The cup 19 is of the same area as the valve seat and as it is exposed tothe inlet pressure it balances the effect of that pressure on the valvehead. The upper end of the stern after passing through a bearing in thecap 22 is secured in a diaphragm 23 which is clamped around itsperiphery by a cover 24 and separates a lower chamber 25 open toatmosphere from an upper chamber 26 to which liquid under pressure issupplied by the pump as described below.

The lower end of the valve stem is guided in a bearing in an invertedcap 27 depending into a chamber divided by a diaphragm 28 into an upperchamber 29 open to atmosphere and a closed lower chamber 30 forming arecuperation chamber for the pumped liquid. The diaphragm takes care ofany fluctuations in the volume of the liquid. The space within the cap27 is sealed by a rolling diaphragm 31 attached to the underside of thevalve.

The pump motor 32 which is a wholly enclosed shaded pole motor islocated in a chamber 33 around which gas after passing through the valveflows to the outlet by way of passages 34 and 35. The chamber 33 iswholly filled with the operating liquid which is preferably a siliconefluid having high stability, constant viscosity, and compatibility withthe materials in the unit with which it comes into contact.

At its lower end the chamber 33 is in communication by way of a passage36 with the chamber 30. The motor drives an impeller 37 located in alateralextension of the chamber 33 and this extension is incommunication by way of a passage 38 with the chamber 26 above thediaphragm 23, and also by way of a passage 39 with a plate valve 41controlling the return of liquidto the chamber 33. This valve, whichcooperates with a seat leading into the upper end of the chamber 33, iscarried on the lower end of a stem42 passing upwardly through an openingin a ring 43 adjustably screwed into a cup 44 mounted in the lower endof a chamber 45, the stem being sealed by a diaphragm 46. The upperendof the stem is secured in a diaphragm 47 closing the upper end of thechamber 45 and clamped around its periphery by a cover 48; The spacebelow the diaphragm is open to atmosphere but the space within the coverabove the diaphragm is in communication by way of a passage 49 with thegas outlet.

The outlet gas pressure acts downwardly on the diaphragm 47 inopposition to the upward force exerted by a spring 51 located betweenthe diaphragm and the ring 43 by which the spring loading can beadjusted.

Mounted on the cover 47 is a thermostatic control of known type in whicha bellows 52 located. within a casing 53 is exposed externally to thepressure of a. liquid in a bulb which is sensitive to thetemperature ina boiler or other appliance heated by gas supplied through the 'valve.The bulb is connected to the casing 53 by a pipe 54. The bellows isattached to a stem 55 in alignment with and adapted to act on the stem42 of the valve 41. n

To open the valve the motor is switched on and delivers liquid underpressure to the chamber 26 whereby the diaphragm 23 moves the valve stem17 downwardly to move the valve head 13 away from its seat and allow gasto flow to the outlet and so to the appliance.

1f the outlet pressure, that is the pressure of the gas supplied to theappliance, rises above a predetermined value it urges the diaphragm 47downwardly against the action of the spring 51 and opens the plate valve41 so that liquid from the extension can return to the chamber 33.. Thisreduces the liquid pressure above the diaphragm 23 and allows the valveto close wholly or partially.

When the outlet pressure falls again the valve 41 closes and thepressure above the diaphragm 23 increasesand the gas valve opens whollyor partially so that a substantially constant governed output gaspressure is automatically maintained.

Also when the temperature in the appliance to which the bulb of thethermostatic control is exposed reaches a predetermined value thebellows 52 opens the plate valve 41 with the same effect, the flow ofgas being restored or increased as the temperature falls again and thebellows contracts.

in the known types of gas valve actuated by hydraulic pressure generatedby a motor-driven pump the pump is usually a fixed displacement pump andthe motor whenswitched on runs until the hydraulic pressure generated issufficient to open the valve fully. The valve then trips a switch whichdeenergizes the motor and the valve is held open by liquid trappedbetween the pump and the diaphragm acting on the valve until anotherswitch is operated to energize a solenoid which opens a relief valveallowing the trapped liquid to return to a reservoir.

In our improved valve we employ a continuously running motor driving acentrifugal pump producing a limited maximum pressure which can bemodulated by the outlet gas pressure and by the temperature in theappliance supplied with gas through the valve.

If no gas is required on the outlet side the pump simply circulates theliquid without generating any pressure and the valve closes without thenecessity for a solenoid-operated relief valve which is a frequentsource of trouble.

I claim:

1. A gas valve through which gas is supplied to a gas-fired applianceand in which a valve head is urged by a spring into engagement with aseat between a gas inlet and an outlet leading to the appliance, whereinsaid valve head is attached in a diaphragm exposed on one side to liquidpressuregenerated by a centrifugal pump continuously driven by anelectric motor and said motor is sealed and is located in a chamber towhich liquid returns from the pump through a valvewhich is urged towardthe closed position by a spring and is adapted to be moved away from theclosed position by a diaphragm exposed to the outlet gas pressure inorder to control the. pressure of the liquid delivered by the pump, saidvalve and its actuating mechanism and said electric motor and pump beinglocated in a cornmon housing to form a uni! having a gas inlet and anoutlet between which the gas, after passing through the

1. A gas valve through which gas is supplied to a gas-fired applianceand in which a valve head is urged by a spring into engagement with aseat between a gas inlet and an outlet leading to the appliance, whereinsaid valve head is attached in a diaphragm exposed on one side to liquidpressure generated by a centrifugal pump continuously driven by anelectric motor and said motor is sealed and is located in a chamber towhich liquid returns from the pump through a valve which is urged towardthe closed position by a spring and is adapted to be moved away from theclosed position by a diaphragm exposed to the outlet gas pressure inorder to control the pressure of the liquid delivered by the pump, saidvalve and its actuating mechanism and said electric motor and pump beinglocated in a common housing to form a unit having a gas inlet and anoutlet between which the gas, after passing through the valve seat,flows through passages around said chamber containing the motor.